The Instability of Plastic Flow of Metals at Very Low Temperatures. II.

1960 ◽  
Vol 13 (2) ◽  
pp. 354 ◽  
Author(s):  
ZS Basinski
Keyword(s):  
Plastic Flow ◽  
Temperature Rise ◽  
Low Temperatures ◽  
Thermal Instability ◽  
Mechanical Instability

Evidence is presented to show that the load drops observed in most metals at very low temperatures arise from thermal instability rather than mechanical instability of the lattice. Measurements of the temperature rise are described.

The instability of plastic flow of metals at very low temperatures

1957 ◽  
Vol 240 (1221) ◽  
pp. 229-242 ◽  
Keyword(s):  
Plastic Deformation ◽  
Transition Temperature ◽  
Low Temperature ◽  
Plastic Flow ◽  
Temperature Rise ◽  
Aluminium Alloys ◽  
Low Temperatures ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Discontinuous Flow

The low-temperature unstable plastic deformation of aluminium alloys is described. It is shown that discontinuities in the stress-strain curve are caused by a localized temperature rise produced during the deformation. The calculated magnitudes of the drops in load and the transition temperature between smooth and discontinuous flow agree reasonably well with the experimental observations. It is believed that all metals should exhibit unstable deformation at sufficiently low temperatures.

Plastic flow of Fe-binary alloys—I. A description at low temperatures

1981 ◽  
Vol 29 (6) ◽  
pp. 1171-1185 ◽  
Author(s):  
Y.T. Chen ◽  
D.G. Atteridge ◽  
W.W. Gerberich
Keyword(s):  
Plastic Flow ◽  
Low Temperatures ◽  
Binary Alloys

Severe Plastic Deformation of Amorphous Alloys

2008 ◽  
Vol 584-586 ◽  
pp. 227-230 ◽  
Author(s):  
Alex M. Glezer ◽  
Sergey V. Dobatkin ◽  
Margarita R. Plotnikova ◽  
Anna V. Shalimova
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Amorphous Alloy ◽  
Severe Plastic Deformation ◽  
Physical Properties ◽  
Plastic Flow ◽  
Low Temperatures ◽  
Amorphous Alloys ◽  
Thermally Activated ◽  
Different Temperatures

The structure and mechanical properties of amorphous alloy Ni44Fe29Co15Si2B10 after severe plastic deformation (SPD) in Bridgman chamber at the different temperatures (77 and 298 K) have been studied. It is shown that the early stages of the SPD of amorphous alloy cause a noticeable decrease in microhardness HV and significant changes in the physical properties. With increasing the value of SPD the transition from inhomogeneous to homogeneous (or to qualitatively different) mode of plastic flow is observed, which is accompanied by the effects of homogeneous nanocrystallization. The nanoparticle size does not exceed 10 nm. It is established that the thermally activated nanocrystallization processes can occur at very low temperatures (77 K).

scholarly journals Waterfall ice: mechanical stability of vertical structures

2011 ◽  
Vol 57 (203) ◽  
pp. 407-415 ◽  
Author(s):  
J. Weiss ◽  
M. Montagnat ◽  
B. Cinquin-Lapierre ◽  
P.A. Labory ◽  
L. Moreau ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Low Temperatures ◽  
Mechanical Stability ◽  
Pressure Fluctuations ◽  
Northern Italy ◽  
Temperature Cycle ◽  
Internal Stresses ◽  
Air Cooling ◽  
Mechanical Instability ◽  
Photographic Survey

AbstractWe present a study of the mechanical (in)stability of the ephemeral waterfall ice structures that form from the freezing of liquid water seeping on steep rock. Three vertical structures were studied, two near Glacier d’Argentière, France, and one in the Valsavarenche valley, northern Italy. The generation of internal stresses in the ice structure in relation to air- and ice-temperature conditions is analyzed from pressure sensor records. Their role in the mechanical instability of the structures is discussed from a photographic survey of these structures. The main result is that dramatic air cooling (several °Ch−1 over several hours) and low temperatures (<−10°C), generating tensile stresses and brittleness, can trigger a spontaneous or climber-induced mechanical collapse, leading to unfavorable climbing conditions. Ice internal pressure fluctuations are also associated with episodes of marked diurnal air-temperature cycle, with mild days (few above 0) and cool nights (few below 0), through the occurrence of water ↔ ice phase transitions within the structure. These ice internal stress fluctuations seem, however, to have a local influence, are associated with warm (near 0), wet and therefore particularly soft ice and do not trigger a collapse of the structure.

scholarly journals The Effect of Insulation Characteristics on Thermal Instability in HVDC Extruded Cables

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 550
Author(s):  
Bassel Diban ◽  
Giovanni Mazzanti
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Electric Field ◽  
Temperature Rise ◽  
Thermal Instability ◽  
Analytical Calculation ◽  
High Voltage Direct Current ◽  
Stability Diagrams ◽  
High Dependency ◽  
Insulation Thickness

This paper aims at studying the effect of cable characteristics on the thermal instability of 320 kV and 500 kV Cross-Linked Polyethylene XLPE-insulated high voltage direct-current (HVDC) cables buried in soil for different values of the applied voltages, by the means of sensitivity analysis of the insulation losses to the electrical conductivity coefficients of temperature and electric field, a and b. It also finds the value of dielectric loss coefficient βd for DC cables, which allows an analytical calculation of the temperature rise as a function of insulation losses and thermal resistances. A Matlab code is used to iteratively solve Maxwell’s equations and find the electric field distribution, the insulation losses and the temperature rise inside the insulation due to insulation losses of the cable subjected to load cycles according to CIGRÉ Technical Brochure 496. Thermal stability diagrams are found to study the thermal instability and its relationship with the cable ampacity. The results show high dependency of the thermal stability on the electrical conductivity of cable insulating material, as expressed via the conductivity coefficients of temperature and electric field. The effect of insulation thickness on both the insulation losses and the thermal stability is also investigated.

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